The 7 Layers (Osi Model)

Hello Everyone,

If you are reading this you must have listened from a lot of people about the importance of ‘The OSI model’ in networking. Let me present you with a quick read on the mentioned topic……………………(Here, we start)

It’s all about -

  • PHYSICAL LAYER — — — — — — —(Layer 1)

  • DATA LINK LAYER — — — — — — — (Layer 2)

  • NETWORK LAYER — — — — — — — -(Layer 3)

  • TRANSPORT LAYER — — — — — — — (Layer 4 )

  • SESSION LAYER — — — — — — — — (Layer 5)

  • PRESENTATION LAYER — — — — — (Layer 6)

  • APPLICATION LAYER — — — — —(Layer 7)

  • (A) PHYSICAL LAYER — — — — — — — - (Layer 1)-

    • Here, The data is transmitted over the network in the form of bits.

    • Examples- Ethernet Cables, Fibre Optic Cables, Hubs, Wireless Access Points, Bluetooth, etc.

  • (B) DATA LINK LAYER — — — — — — — (Layer 2)-

    • Here, encapsulation of data into frames takes place. Then, the transmission of these frames takes place over the network.

    • Detection of error and it’s correction also takes place here.

    • Another function includes Identification of network devices using their MAC address.

    • This layer is also responsible for flow control.

    • Examples- Switches, Bridges, etc.

  • (C) NETWORK LAYER — — — — — — — -(Layer 3)-

    • Whenever we talk about this layer, we talk about routing, addressing(IPv4, IPv6), Switching, etc.

    • Here, data flows in the form of packets.

    • Examples- Routers for traffic forwarding, IPv4 Protocol and IPv6 Protocol for IP addressing, Internet Control Message Protocol (ICMP) for troubleshooting, etc.

  • (D) TRANSPORT LAYER — — — — — —- (Layer 4 )-

    • Here, the concept of TCP(Transmission Control Protocol) and UDP(User Datagram Protocol) comes into play.

    • If you are wondering what are the above-mentioned protocols. You can find out about them on the internet pretty easily.

    • The only thing I should mention here is TCP is more reliable (due to 3-way handshake method) than UDP.

    • Whenever data travels in this layer, it's in the form of SEGMENTS (if using TCP) or DATAGRAMS (if using UDP).

    • Examples- TCP, UDP, Firewalls, etc.

  • (E) SESSION LAYER — — — — — — — — (Layer 5)

    • The main purpose includes setting up sessions, maintaining these sessions and closing a session

    • Here, the session is basically a connection or a conversation that is kept separate from other sessions.

    • Examples- NetBIOS (Used by computers to share files over a network)

  • (F) PRESENTATION LAYER — — — — — -(Layer 6)

    • In this layer data formatting(for proper compatibility between devices) and data encryption takes place.

    • Example- Open any mail you had received. In that mail press on view details. there will be a field mentioned as security in there, which is designated as TLS(Transport Layer Security). If it’s not TLS then please be careful.

    • Other Examples- SSL, GIF, JPG, TIF, SVG, PNG, HTML, XML, PHP, JavaScript

  • (G) APPLICATION LAYER — — — — — — (Layer 7)

    • This layer provides application services.

    • With the help of these services, user communicate with the computer.

    • Example- Domain Name Service (DNS), Remote Access (TELNET, SSH), Web Browsing (HTTP, HTTPS), E-mail (POP3, IMAP, SMTP) etc.

Well, you can put it like this (To Remember)-

Perfection_Do_Not_Tell_Someones_Positive_Attitude

or

You can make your own short key phrases

Make your own key phrase using these 7 layers and

Comment down below